<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>排行动画</title>
    <style>
      html,
      body,
      div,
      ul,
      li,
      img,
      span {
        padding: 0;
        margin: 0;
      }

      ul,
      li {
        list-style: none;
      }

      span {
        display: inline-block;
      }

      img {
        vertical-align: top;
      }

      #box {
        padding: 20px;
        height: 700px;
      }

      #box ul {
        padding-left: 20px;
        position: relative;
      }

      #box li {
        margin-left: 60px;
        height: 28px;
        box-sizing: border-box;
        position: absolute;
        line-height: 28px;
        transition: transform ease 1s, opacity ease 1s;
        opacity: 0;
        background: #ddd;
        border-radius: 20px;
        box-shadow: inset -5px 0px 25px rgba(0, 0, 0, 0.4);
      }

      #box li .name {
        position: absolute;
        left: -60px;
        white-space: nowrap;
      }

      #box li .count {
        margin-left: 15px;
        position: absolute;
        left: 100%;
        font-size: 18px;
        letter-spacing: 1px;
        color: #fff;
        font-style: italic;
        text-shadow: 1px 0 2px #000, 0 1px 2px #000;
      }
    </style>
  </head>
  <body>
    <div id="box">
      <h3>销量排行</h3>
      <ul id="list"></ul>
    </div>
    <script>
      class Animate {
        constructor() {
          this._baseData
          this.htmlDOMData = []
        }

        init() {
          // 初始化数据
          this._initArr()

          // 创建动画
          this._createAnimate()

          // 新增事件
          this._addNewAnimate()
        }

        _initArr() {
          let data = []

          for (let i = 0; i < 10; i++) {
            let _obj = {
              id: `id${i + 1}`,
              name: `第${i + 1}位`,
              count: parseInt(Math.random() * 800)
            }
            data.push(_obj)
          }
          this._baseData = data
        }

        _createAnimate() {
          // 如果是第一次先创建DOM元素，不是就开始动画
          for (let i = 0; i < 5; i++) {
            if (i === 0) {
              this._firstCreate()
            } else {
              setInterval(() => {
                this._beginAnimate()
              }, i * 3000)
            }
          }
        }

        _firstCreate() {
          this._first = false
          let bar = document.querySelector('#list')

          this._baseData.sort((l, n) => n.count - l.count)
          this._baseData.forEach((_data, index) => {
            let li = this._createLiDom(_data, index)
            bar.appendChild(li)

            this.htmlDOMData.push({
              id: _data.id,
              el: li
            })
          })
        }

        // 随机生成bar背景颜色
        _createBgColor() {
          return `rgb(${parseInt(Math.random() * 255)}, ${parseInt(Math.random() * 255)}, ${parseInt(Math.random() * 255)})`
        }

        // 创建单个bar元素
        _createLiDom(data, index) {
          let li = document.createElement('li')
          let name = document.createElement('span')
          let count = document.createElement('span')

          name.classList.add('name')
          name.innerText = data.name

          count.classList.add('count')
          count.innerText = data.count

          li.style.opacity = 1
          li.style.width = `${data.count}px`
          li.style.background = this._createBgColor()
          li.style.transform = `translateY(${index * 40}px)`

          li.append(name, count)
          return li
        }

        // 开始动画的函数
        _beginAnimate() {
          let bar = document.querySelector('#list')
          let newData = this._reoederBasedata() // 重排数据

          newData.forEach((_l, i) => {
            this.htmlDOMData.some((n, k) => {
              if (_l.id === n.id) {
                n.el.style.width = `${_l.count}px`
                n.el.style.transform = `translateY(${i * 40}px)`
                n.el.lastElementChild.innerText = _l.count
              }

              if (n.isNew) {
                bar.appendChild(n.el)
                n.isNew = false
              }
            })
          })
        }

        // 重新排序
        _reoederBasedata() {
          this._baseData.forEach((_d) => {
            _d.count = parseInt(Math.random() * 800)
          })

          return this._baseData.sort((l, n) => n.count - l.count)
        }

        // 添加新数据的动画
        _addNewAnimate() {
          let num = 0,
            timer = null

          timer = setInterval(() => {
            num += 1
            this._addNewData()

            if (num > 3) {
              // 新增到4个之后就清除定时器
              num = 0
              clearInterval(timer)
            }
          }, 6000)
        }

        // 添加新数据
        _addNewData() {
          let len = this._baseData.length
          let _new = {
            id: `id${len + 1}`,
            name: `第${len + 1}位`,
            count: parseInt(Math.random() * 800)
          }
          let li = this._createLiDom(_new, len + 1)

          this._baseData.push(_new)
          this.htmlDOMData.push({
            id: `id${len + 1}`,
            el: li,
            isNew: true
          })
        }
      }

      let myAnimate = new Animate()
      myAnimate.init()
    </script>
  </body>
</html>
